Four sea lions were used in the film. There was a base holding facility with a filtered pool system and around-the-clock security for the animals. On location, two large metal "pools" (2 feet x 6 - 7 feet in diameter), were provided for the sea lions. The area was enclosed by fencing and someone was with the animals at all times. A tent was set up for shade when needed. The sea lions were fed and trained with their daily, weighed, diet of fish.

When the kids "rescue" Slappy, they put him in the back on their bus. Later, he is seen on the ground, after he supposedly jumped from the bus. This scene was shot in cuts. Trainer #1 placed the sea lion's stand in front of the bus steps while trainer #2 hid inside the bus. Trainer #2 cued the animal with verbal commands to go inside. Then he placed the sea lion on a seat and the children naturally interacted with the animal. An animatronic sea lion was used for the portion of Slappy jumping from the bus.

At one point, Slappy is seen in a hot tub which happens to be at Mr. Morgan's, (the head master at school), house. As Slappy plays in the hot tub, the kids feed him raw fish. Some of them toss the fish through the air and Slappy catches it in his mouth. The trainer placed the animal on his mark and cued him with verbal commands.

Gordon, Mr. Morgan's dog, starts barking and doing tricks while begging for fish. Later, Gordon falls into the tub with Slappy. When Mr. Morgan arrives home, he picks up the wet dog and walks into the house. This scene was shot in cuts. The trainer placed the dog on his mark and cued him with verbal commands and a food reward.

Slappy is lying in bed with Witz, one of the "stinkers", with the covers pulled up to his chin. During the night Witz sneezes and kicks Slappy out of bed. The next day, after Witz leaves the room, Slappy notices a bottle of cough medicine on the night-stand and drinks it. Then he sees a bar of ex-lax and gobbles it down. In a few minutes, Slappy's stomach starts making awful grumbling sounds and he heads for the bathroom. Witz sprays air freshner as Slappy sits on the toilet. This scene was shot in cuts. When the sea lion drinks the cough medicine it is actually colored water. He is only seen sniffing the ex-lax, we assume he ate it. The trainer placed him on the toilet and cued him with verbal commands to "stay".

The kids decide it is time to take Slappy home to the ocean. They place him in an antique claw footed bathtub on wheels and attach a rope to Loaf's bike. The tub is seen tooling down the road behind Loaf and the other children as they make their way to the beach. An animatronic sea lion was substituted for the real one in the scenes where the tub is actually moving.

Upon arriving at the beach, Slappy does not want to go into the water. After several attempts to coax him in, the kids finally try to roll him to the water. Slappy decides he likes the tub better so he climbs back inside. A tarp was placed on the sand and the trainer cued him with verbal commands to roll.

Later, the kids leave Slappy in his tub behind a shed at the school and proceed to the parents' day festival. Roy, the caretaker at the school, finds Slappy and they each are scared by the other. Slappy jumps out of the tub and disappears in the tall grass, heading for the parents' day festival. This scene was shot in cuts. The sea lion was cued by two trainers for the behavioral looks back and forth. For the segment of the sea lion jumping out of the tub, the trainer placed the animal in the tub and cued him with verbal commands to jump out and praised him with a food reward.

At the festival, Slappy pokes his head through a curtain at the back of a booth where he sees some goldfish in plastic bowls. He picks up the bowls and tosses them around. He hears Roy and a hedge trimmer bounding through the crowd, so he runs across the table. Slappy, with Roy in hot pursuit, runs through the French pastry booth to the chili booth where he darts under the table. Later, Slappy pokes his head out of the bushes and Morgan grabs a streamer hanging around his neck. This scene was shot in cuts. The trainer placed the sea lion on his platform behind a curtain and cued him to poke his head through a slit. The bowls that were tossed around contained fake fish. A few bowls on the outer rim of the table contained real fish. A trainer was at the end of the table and cued him to travel down the table and exit. A very long table with a cloth on top was used for the shot of Slappy underneath. A trainer at one end cued him for his behavioral looks.

While under the table, Slappy knocks a leg out and the table falls. The legs and table were controlled by monofilament. The pole on the table top extends and fell after the sea lion had passed.

The "stinkers" find Broccoli's hide-out, where he is keeping Slappy, at an abandoned Saw Mill. When they arrive, Broccoli is standing next to a fire ring holding an electric prod and a dead fish. Slappy is sitting on a barrel on the other side of the hoop. Broccoli nudges Slappy with the prod and he supposedly jumps through the hoop, landing on the floor. This scene was sot in cuts. The sea lion sits on a barrel with a chain wrapped loosely around its neck. The actor is holding a fake cattle prod. He places it behind the sea lion to simulate prodding its back-side. At that moment the trainer, off camera, cues the animal to come down from the barrel and lay flat on the ground "head down". The chain around its neck was plastic. An animatronic sea lion was used when the cattle prod is seen coming into contact with the animal.

When the kids enter the room where Slappy is, they see him attached to a beam by a chain around his neck. Slappy tugs on the chain with all of his strength, pulling the beam away from the foundation and collapsing the structure. Loaf pulls the collar over Slappy's head and frees him. This scene was shot in cuts. Balsa wood was used for the beams. Trainer #1 placed the sea lion on its mark for the establishing shot while trainer #2 holding the chain, cued it to move forward. Trainer #2 pulled the chain taut at the precise moment that the beam was triggered to fall. The sea lion was never in any danger of coming into contact with the beam.

The "Stinkers" place Slappy in the antique tub, however, they have made a few changes. It is now equipped with a bucket seat and a steering wheel. Another seat is attached to the rear for a brake person with two levers made out of hockey sticks. Loaf releases the hockey sticks and the tub starts to roll down the steep mountain. Broccoli is in close pursuit in his van and he nudges the tub with the van's bumper. An animatronic sea lion was used for this scene. The only time a real lion was used was for establishing shots.

Mr. Morgan has the school on a field trip for bird watching in the woods. Gordon begins to bark as the tub bursts through the bushes. Gordon jumps into Morgan's arms right before Morgan is hit head on by the tub, tossing dog and owner into the air. Gordon lands in Loaf's arms. Slappy and Gordon lick. This scene was shot in cuts. A secured platform made of plywood and an apple box was about 2 feet off of the ground. When the dog is caught by the actor, the trainer was standing on a platform about 4 to 5 feet above and merely dropped the dog into his outstretched arms. The actor had a treat in his upper pocket and the trainer showed it to the animal before he jumped.

Later, Slappy is seen at his old home at the aquarium. The kids are all there to see him. He does several tricks and Morgan ends up in the water with him. For this scene several trainers were strategically placed around the pool. The trainers cued him with verbal commands with food as a reward.

There are several scenes where dead fish are being used as food or bait for the sea lion. All of these fish were purchased at a fish market. A fake beaver was used for the scene where Broccoli is bitten and a struggle ensues. All octopus scenes where animatronic.